Hydraulic spacer



Sept? 5 1960 A. H. LEEQE 2,954,016

HYDRAULIC SPACER Filed March 13, 1959 I FIG. I

. l 5? "r II" 52 1N VEN TOR. Amen-r H. Lee-s5.

ATTORNEY Patented Sept. 27,1960

2,954,016 HYDRAULIC SPACER Albert H. Leese, Royal Oak, Mich., assignor to Cur-tiss- Wright Corporau'on, Utica Division, Utica, Mich., a corporation of Delaware Filed Mar. 13, 1959, Ser. No. 799,130

7 Claims. (Cl. 123-90) The present invention relates to hydraulic spacers and more particularly toa manually adjustable hydraulic spacer incorporated in a valve tappet assembly for an internal combustion engine.

In internal combustion engines employing poppet valves it is always important to maintain a designed clearance in the valve actuating mechanism. Such clearance is usually located between the cam lobe and the cam follower. If the clearance is too small, the valve may not close under all operating conditions or, alternatively, if it is too great there may be excess wear on the cam follower because the cam lobe does not strike it at the proper angle. 1

Various means have been suggested and employed to allow adjustment in dimension so as to permit maintenance of the specified clearance after engine parts have become worn through use. The present invention discloses a device of simple construction for varying the thickness of. a valve tappet which has many advantages over the prior art and is particularly adapted to large engines having overhead cams acting directly abovethe poppet valve assembly. It is to be understood, however, that it is equally adaptable in valve applications of other types and configurations.

It is an object of the present invention to provide an adjustable valve tappet spacer capable of accurately maintaining a specified clearance between the cam and camfollower of a poppet valve engine.

It is still another object of the present invention to provide an adjustable hydraulic tappet spacer which contains an hydraulic fluid that may be displaced to control the thickness of the head of the tappet body.

These and further objects of the present invention will become apparent from the following discussions and the accompanying drawings in which:

Figure 1 is a perspective view of a tappet body incorporating the manually adjustable hydraulic spacer of the present invention;

' Figure 2 is an elevational view, partly'in section, of a portion of an engine incorporating the spacer of Figure 1; and

Figure 3 is an elevational view in section of the manually adjustable hydraulic spacer.

Referring now to the drawings wherein like reference numerals define like parts, in Figure 1 a cup-shaped valve tappet body is disclosed which incorporates the adjustable hydraulic spacer mechanism its preferred form. Figure 2 discloses a portion of a poppet valve internal combustion engine having a cylinder block 12 and a cylinder liner 14 secured therein. The liner 14 and a cylinder head 16 combine to define a combustion chamber 18. Reciprocally mounted within the cylinder liner 14 is a piston, not shown, which receives and transmits the combustion forces for doing useful work. The cylinder head 16 is a cored casting having cooling water passages 20 and intake and exhaust gas passages. In Figure 2 only the intake passage 22 is shown; however, the exhaust gas passage is of similar construction.

The intake passage 22 is sealed from the combustion chamber 18 by a poppet valve 24 having a valve head 26 and a valve stem portion 28. The valve head 26 is adapted to have a sealing contact with a valve seat 30 formed at the mouth of the intake passage 22. The valve 7 stem 28 is reciprocally received within a sleeve member 32 which functions as a liner or bearing surface for the sliding valve stem 28.

The sleeve 32 is received within a vertical bore 33 formed in the cylinder head 16 and has an upstanding cup member 34 integrally formed on the upper end of the sleeve 32. The upper end of the valve stem 28 has a collar-like spring retainer 36'detachably aflixed thereto. There is provided a pair of coaxial valve springs 38'and 40 interposed between the spring retainer 36 and the inner fioor of the cup member 34. Telescopingly re- 5 ceived within cup member 34 is the tappet body 10.

Tappet body 10 is of an inverted cup shape and fits over the upper end of the valve stem 28a.

Tappet body 10 constitutes a cam follower and its upper surface 42 receives the sliding face of -an eccentric cam lobe 44 carried by a camshaft 46. As is well known, the rotation of the camshaft 46 is coordinated with the movement of the piston so that the cam lobe 44 will bear against surface 42 to drive the poppet valve 24 downwardly at thedesired moment in the cycle. This action will unseat the valve head 26 and permit the reception of combustion supporting air through passage 22 into combustion chamber 18.

In order to maintain perfect combustion it is necessary that the valve head 26 be seated at all times other than when it is intended that combustion supporting air be admitted to the combustion chamber 18. It is for this reason that a clearance c is provided between the minimum radius of the cam 44 and the upper surface 42 of the tappet body 10 when valve 24 is fully seated. This clearance will ordinarily be in the order of .005 to .015 inch. 1

Due to manufacturing tolerances and wear encountered during the operation of an engine, it is necessary from time to time to make adjustments in the working parts so as to obtain a constant clearance c. Such adjustment is permitted by the present invention. I V

In Figure 3 details are shown of the construction of the tappet body 10 wherein a vertical cylinder bore 50 is provided and has slidably disposed therein a piston member 52; Piston 52 has a circumferential groove 54 for the reception of a flexible sealing element 56 disclosed in the drawing as being preferably of the O-ring type. Ring 56 assures a sealing contact between the piston 52 ancl the cylinder 50. There is also provided in the head of the tappet body 10 a horizontal bore 58 which is communicatively connected with the cylinder 50 by means of an orifice 59. The wall of bore 58 is threaded to receive a plug 60. The plug 60 is characterized by a toolreceiving socket 62 in its outer end and a flexible sealing member 64 disposed somewhere along its periphery.

An incompressible fluid is trapped in the chambers defined by the bores 50,58 and between piston 52 and plug 60. Sealing elements 56 and 64 prevent the passage of fluid beyond the piston 52 or plug 60 respectively. It is thus apparent that as the plug 60 is threaded in or out, hydraulic fluid will be forced through the orifice 59 and into or out of the cylinder 50 and consequentially piston 52 will correspondingly be forced into or out of the cylinder 50. It is thus obvious from the foregoing structure that the dimension of the valve body between the upper face 42 and the lower face 66 of piston 52 can be controlled by the lateral positioning of plug 60. Because the plug 60 is smaller than the piston 52, greater axial movement of the plug 60 will be required for a corresponding shift of the piston 52, permitting an accurate adjustment of that dimension.

A bleed passage 68 is provided in the tappet body so that the chambers of bores 50 and 58 may be filled with hydraulic fluid, the piston 52 inserted in position, and then plug 60 screwed into the bore 58. As the plug 60 is threaded into position excess fluid will be forced out through the bleed passage 68 until the plug 60 is well received within the bore 58 and the sealing element 64 has passed the mouth of passage 68. This activity thus assembles the tappet body 10 for installation into the engine. Referring to Figure 2, it is seen that when properly located face 66 of piston 52 bears against the end 28a of valve stem 28.

When the tappet 10 is located in the valve assembly as seen in Figure 2, a feeler gauge corresponding to the dimension c in thickness is interposed between the cam 44 and the tappet face 42. A tool is then inserted in socket 62 and the plug 60 is adjusted horizontally causing a vertical adjustment of the piston 52. When the horizontal adjustment of plug 60 is achieved which gives the desired clearance c as indicated by the feeler gauge, then the valve assembly is ready for operation.

Because the fluid trapped between the piston 52 and plug 60 is of constant volume, clearance 0 will be maintained until wearing of the valve head 26, valve seat 30, tappet face 42, or of the cam 44 has occurred. Such wearing will change the clearance, and it will then be necessary to again adjust the spacer to maintain the desired clearance c. This further adjustment is achieved by merely screwing the plug 60 in or out until the clearance c is again realized.

The foregoing constitutes the preferred form of the present invention. Variations will occur to those skilled in the art which will fall within the scope and spirit of the following claims.

I claim:

1. A valve tappet spacer having a blind hole therein, a piston slidably received within said hole, a second hole intersecting said first mentioned hole in the region of said hole normally between the blind end thereof and said piston and having a plug threadably received therein, and hydraulic fluid disposed in said holes and trapped between said piston and said plug.

2. A valve tappet spacer assembly having a cup shaped cam follower, said follower having a head portion with a blind hole therein, a piston slidably received within said hole, a second hole intersecting said first mentioned hole in the region of said first hole normally between the blind end thereof and said piston and having a plug threadably received therein, and hydraulic fluid disposed in said holes and trapped between said piston and said P g.

3. In an internal combustion engine having cam actuated poppet valves a cup shaped cam follower, said 60 follower having a head portion with a longitudinal blind hole opening toward the inside of said cup shaped cam follower, a piston slidably received within said hole, a transverse hole communicating with said first hole in the region normally between the blind end thereof and said piston, a plug threadably received within said second hole, and hydraulic fluid disposed in said holes and trapped by said plug and said piston.

4. In a valve tappet assembly an adjustable thickness device comprising an element having a blind longitudinal bore and a piston slidably received within said bore, a second bore communicatively connected to said first mentioned bore in the region normally between the blind end of said bore and said piston and having a plug member threadably received therein so as to define a sealed chamber between said piston and said plug.

5. In an internal combustion engine having cam actuated poppet valves comprising serially disposed cam and poppet valves a' cam follower and adjustable spacer device interposed between said cam and said valve, said device having a longitudinal bore directed away from said cam, a piston slidably received within said bore, a second bore in said follower communicating with said first mentioned bore in the region normally between the closed end thereof and said piston, a plug threadably received within said second bore, and hydraulic fluid disposed in said bores and trapped between said plug and said piston.

6. In a valve tappet assembly an adjustable thickness device comprising an element having a blind longitudinal bore and a piston slidably received within said bore, a second bore communicatively connected to said first mentioned-bore in the region normally between the closed end of said first bore and said piston and transverse thereto, said second bore being of substantially lesser diameter than said first mentioned bore, and a plug member threadably received within said second bore so as to define a sealed chamber between said piston and said plug.

7. A hydraulic spacer for placement between a tapper element and a tap receiving element, which comprises: a piston member; a piston receiving member having a piston chamber open at one end and closed at the opposite end with said piston member being slideably disposed therein and normally spaced from said closed end and an auxiliary, hydraulic fluid chamber with an interconnecting passageway therefrom to said piston chamber in the region thereof normally between said piston member and said closed end of said piston chamber, one of said piston member and piston receiving member being adapted to be in combination with one of said elements; and adjustment means for adjusting the hydraulic fluid capacity of said auxiliary chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,613,117 Miller Ian. 4, 1927 

